Method for producing oil gas



Unite trates arent hice May 3i, F3555 Marston non PRoDUeING on. GAS

.lohn S. Haug, Philadelphia, Pa., assigner to United Engineers & Constructors Inc., Philadelphia, Pa., a corporation of Deiaware Application March 29, 1951, Serial No. 218,125 6 Claims. (Cl. L8-211) The present invention relates to a novel method for producing combustible gas, and more particularly it relates to a method for the pyrolysis of hydrocarbon oil to form combustible gas, referred to as oil gas, especially oil gas of a type suitable for supplementing the supply of natural gas, whereby certain disadvantages of prior oil gas-making processes and apparatus are overcome.

The conventional method of making oil gas, as it has been practiced for years, involves, in general, a cyclic operation in which, during one part of the cycle, fuel is burned and the hot products of combustion passed through a bed or beds of refractory material, generally checkerorick, storing heat therein; and, in another part of the cycle, vaporizing oil by spraying it on the hot checkerbrick and passing it, with or without steam, through the hot refractory material where it is cracked and fixed into a stable combustible gas. Normally a somewhat restricted space is provided in advance of the refractoryI material wherein, during the heating step, the fuel is ignited and some combustion takes place. A large portion ot the combustion, however, generally takes place within the refractory bed and this gives rise to certain disadvantages. In the first place, much of the fuel becomes swept well along the passageways in the refractory bed before combustion takes place, andthen, he cause of incomplete mixing of the fuel and air caused by the restrictive effect of channels in the checkerbrick, some of the fuel may remain unburned or only partly burned, that is, with the formation of carbon monoxide and lamp black. This means not only ineicient operation from the standpoint of fuel waste, but, as' a practical matter it also means that, in'ordei` to store sucie'nt heat for the gas-making run, the heating portions of the cycles must be longer than would be the case if complete mixing of the fuel and air for contoustion were provided before the refractory bed. With less efficient combustion,

iuch of the time which could be occupied by the gasmaking operation is actually taken up by heating. Attempts to insure more complete combustion are made by supplying, during the heating step, a considerable excess of air over that theoretically required for completecombustion. However, the use of excessive amounts of air is not only undesirable because of increased waste heat losses, but results in a reduction of heating rate, since lessfuel can be burned with a given air supply, and this leads again to loss of generating capacity. This latter feature is particularly apparent in the case of converted carburetted water gas apparatus which utilize an existing air supply, and do not have large enough supply connections and passages to handle excessive quantities of air and combustion gases, without resort to abnormally high blast pressures. Generation of such pressures is expensive in investment and operating costs and there is danger that high pressures in the apparatus would cause heating gases to break the water seal in the Wash box and be carried into the relief holder to mix with the make gases.

l have found that the ideal solution would be to prolli vide sufficient space in the combustion zone such that the length of ame travel provided and the volume for mixing of the fuel and air through turbulence, be such that substantially complete combustion of the fuel occurs before the hot gases reach the heat storage refractory material. By such a procedure, a higher heating rate could be attained with a given air suppiy than by the former processes discussed above, and, in addition, due to the higher flame temperatures of the combustion prodducts with minimum excess air, the heat storage refractory material is thereby more quickly heated. Where the process and apparatus are to be used chiefly to satisfy peak load demands, particularly as in supplementing a natural gas supply, low investment costs are essential for the reason that the plant would only operate during a relatively short portion of the year and investment charges per unit of gas manufactured would be correspondingly increased. lt would, therefore, be particularly advantageous to provide migas-making equipment overcoming the above disadvantages without the necessity of constructing large or long combustion chambers and utilizing, to the best advantage, existing carburetted water gas apparatus.

Other factors influence the design of migas-making equipment or limit the modication of existing carburetted water gas apparatus to provide oilgasmai ing apparatus. For instance, the pyrolysis of heavy oil necessarily produces coke deposits, fouling of equipment by which must be prevented, and the removal of which must be facilitated. While carburetted water gas equipment has, in the past, been converted to oil gas equipment, such conversion either has not eliminated the limitations of the carburetted water gas apparatus with respect to the coke problem, or has necessitated such excessive modification of the carburetted water gas apparatus as to involve considerable expense.

`lt is a principal object of the present invention to provide a novel method for manufacturing oil gas whereby the above-mentioned disadvantages and limitations of existing practice are overcome.

` Another object is to provide a novel process for producing oil gas wherein substantially complete combustion of the fuel, without large amounts `of excess air, is insured.`

Another object is to provide a process for producing oil gas wherein the proportion of migas-making time during a cycle may be substantially increased, and the proportion of heating time may be substantially decreased as compared to prior oil gas practice, so as. to provide a material increase in gas-generating capacity as compared with known procedures.

Still another object is to provide a novel oil gas process providing increased eliciency and economy with respect to the heating operation.

A further object is to provide a novel process for pro ducing oil gas which may involve slight but significant modication of existing carburetted water gas apparatus, particularly where the above-discussed limitations of prior converted carburetted water gas apparatus are overcome.

Other objects will be apparent from a consideration of the following specification and the claims.

The cyclic process of the present invention comprises, in one part of the cycle, forcing an ignited mixture of fluid, fueland air downwardly from a point near the top of a confined, relatively empty combustion zone having an outlet near the top thereof whereby the resulting ame descends toward the bottom of said zone, reverses itself and ascends toward the top ot said Zone; withdrawing the resulting hot combustion products from said outlet near the top of said zone; passing said hot products of combustion through heat storage refractory material storing"heat therein; and, in another part of said cycle, in-

troducing oil into said zone, vaporizing the oil therein; withdrawing the resulting vaporized oil through said outlet near the top of said zone; passing said vaporized oil through said hot heat storage refractory material, pyrolyzing said oil therein into a combustible gas, and withdrawing said gas to storage.

The present invention may be more readily understood from a consideration of the drawings in which:

Figure l is a sectional elevation view of an apparatus which may be employed in accordance with the invention, and

Figure 2 is a sectional elevation view of another form of apparatus which may be employed in carrying out the invention.

Figure 3 is an elevational view, partly in section, of a modification of the apparatus illustrated in Figure 2.

Referring to the apparatus shown in Figure l, 1 is a refractory-lined chamber, which may be a conventional superheater of a carburetted water gas set with appropriate modification as shown and described. 2 represents a confined refractory-lined relatively empty space which serves as a combustion chamber during the heating step and as a vaporizing chamber during the gas-making run part of the cycle. 3 represents a bed of refractory heat storage material illustrated in the drawing as tire-brick i arranged in familiar checkerbriclrpattern. 4 represents a stack valve through which products of combustion may pass to the atmosphere. 5 is a conduit through which the combustible product gas may pass to gas-recoveryV equipment which may include the conventional liquid sealed washbox, gas holder, etc. 6 represents a conduit for supplying air to the burner or burners during the heating step and the flow of air through this conduit is controlled as by valve 7. 8 and 10 represent conduits through which iiuid fuel is forced to the combustion chamber, the flow of the fuel through the conduits being controlled by valves 9 and 11, respectively.

12 and 13 represent the fuel burners which may be of any desired type so long as the blast of the ignited mixture of fuel and air is directed or injected generally downward toward the bottom of the combustion space as shown. Although Figure 1 shows two fuel burners, it will be realized that only one, as shown in Figure 2, or any other number of burners may be employed. When a plurality of burners is employed they will generally be disposed about the inner periphery of the combustion space in spaced apart relationship, and preferably in a common horizontal plane. v

14- represents a conduit through which steam, which may be employed, if desired, during the gas-making run, is introduced to the combustion zone, the flow of steam through said conduit being controlled as by valve 15. 16 represents a conduit through which a purging and/or process gas, such as steam, may be forced into the bottom of chamber 2 and the flow through this conduit is controlled as by valve 17.

In the apparatus shown in Figure 1, the outlet for gaseous material from the refractory-lined space 2 is from its top. It will also be noted that the fuel burners are positioned near the top of space 2 so that the downwardly directed iiame must traverse substantially the height of the space in the upward direction before the hot combustion products leave space 2 and enter the heat storage refractory material 3.

In the apparatus shown in Figure 1 no separate inlet is shown for the oil for use during the gas-making run portionof the cycle. Such arrangement is particularly adapted for use in the event the fuel employed is oil of the same type employed in the manufacture of oil gas during the gas-making run. In such case, the oil for pyrolysis may be supplied through conduits 8 and 10, the flow being controlled as by valves 9 and 11, respectively. It may be desirable, for the sake of better controlling the rate, to flow the oil, for example, during the gas-making period, through an independent valved conduit or c0n' duits such as 3a and 10a, the valves 9a and 11a controlling liow during this period. Further in this connection, conduits 8a and 1th: may lead into annular conduits surrounding conduits 8 and 10, respectively, annular spray heads at nozzles 12 and 13, respectively, being provided. This latter embodiment permits the same general injection means to be employed for both fuel and gas-making oil and allows the introduction of the gas-making oil at materially higher rates than that of the fuel. In the event the make oil is not employed also as fuel, or for other reasons, it may be introduced to space 2 by entirely separate means as shown in Figure 2.

With respect to Figure 2, 21 represents a confining refractory-lined relatively empty chamber comprising combustion and vaporizing space 22. 23 represents a second confining refractory-lined chamber containing heat storage refractory material 25 and 24 represents a third confining refractory-lined chamber containing heat storage refractory material 25. The heat storage refractory material in chambers 23 and 24, as shown in the drawing, may be irebrick arranged in the familiar checkerbrick pattern.

The top of chamber 21 is connected to one end, preferably the top, of chamber 23 oy conduit 27, and the other end, preferably the bottom, of chamber 23 is connected to one end, preferably the bottom, of chamber 24 by conduit 28. 29 represents a stack valve through which the products of combustion may pass to the atmosphere, and 30 represents a conduit through which the combustible product gas may pass to a wash box and gas-recovery equipment. The apparatus shown in Figure 2 may be constructed from conventional carburetted water gas equipment, chambers 21, 23 and 24 corresponding to the generator, Carburettor and superheater, respectively, of a conventional carburetted water gas set, appropriate modification being made as shown in the drawing and as described herein.

31 represents a conduit through which air may pass to the fuel burner in chamber 21, the flow thereof being controlled as by valve 32. 33 represents a conduit through which steam may be supplied to the apparatus, the flow thereof being controlled as by valve 34. As shown in the drawing; conduit 33 may be connected to conduit 31 affording a common entry for the steam and for the air into space 22. This is advantageous from the standpoint of preventing the burner from getting excessively hot. 35 represents a conduit through which fuel may be 4supplied to space 22, the flow of fuel therethrough being controlled as by valve 36. 37 represents a conduit through which oil may be supplied to space 22 for pyrolysis in the production of the combustible product gas, the flow of oil through conduit 37 being controlled as by valve 38. 39 represents a burner nozzle for injecting fuel into space 22 for combustion therein, and 49 represents a nozzle through which the oil may be forced for vaporizing and pyrolysis. Although the apparatusillustrated in Figure 2 shows a single burner positioned near the top of space 2 andrdirected downwardly substantially along the axis of the space 22, it will be understood that a plurality of burners may be positioned Y in space 22 as described in connection with Figure l. Similarly, although the apparatus illustrated in Figure 2 shows separate means for introducing malte oil to space 22, it will be understood that, the make oil may be introduced through conduit 35 and injected through nozzle 39. In this connection, and in Figure l, a separate valved conduit connected to conduit 35, or to an annular conduit surrounding conduit 35, may be provided to supply either the fuel or gas-making oil. in addition, although Figure 2 shows but a single separate make-oil-supplying conduit, it will be realized that a plurality of such means may be provided, disposed around the inner periphery of chamber 21 in spaced apart relationship. l

41 represents a conduit through which purging and/or process gas, such as steam, may be supplied to the bottom i of space 22, the ilow of such gas being controlled as by valve 42.

ln Figure 2, optional auxilary or supplemental steam, fuel, air and make oil supply means are shown connected to the top of chamber 23, in case it is desired to introduce one or more of these materials at this point. Thus 43 represents a conduit through which secondary air may be introduced into chamber 23, valve i4 controlling the flow of air therethrough. 45 represents a conduit through which stel may be introduced to chamber 23, valve 45 controlling the flow of steam. i7 represents a conduit through which secondary fuel may be introduced to chamber 23, valve i3 controlling the flow of fuel there through, and #29 represents a secondary burner. 50 represents a conduit through which make oil may be introduced through nozzle 52 into chamber 23, valve 5l conv trolling the vdow of make oil therethrough. As stated previously, if the fuel employed is the same as the malte oil, the oil for the gas-making run, as well as the oil for the heating step, may be introduced through conduit 47.

The apparatus shown in Figure 3 is the same in all respects as that shown in Figure 2 with the exception that the second chamber, 23a, is devoid of heat storage refractory .material filling. The presence of such lilling in the second chamber is not necessary from the standpoint the present invention. ln fact, the apparatus of Figure 3 is particularly applicable when the supplemental gasmalting oil is admitted to the second chamber, especially when such oil is a heavy colte-bearing oil. ln such case the absence ot g material minimizes the possibility of coke deposits cai ing stoppages in the apparatus. The coke which accumulates at the bottom of chambers 21 and 2th' may be periodically removed with minimum difficulty.

Various modifications of the apparatus shown in Figures l, 2 and 3 are possible in accordance with the present invention. Thus, for xample, the apparatus may consist of a two-shell set in which the confined refractory-lined space 2 of Figure l is in one relatively empty shell and wherein the heat storage refractory material 3 may be in a separate second shell, instead of the latter being superposed on the former in a single shell as shown in Figure l. ln this case, the top of thc shell containing space 2 may be conne-'ted to one und of the shell containing the heat storage ret' ery material 3, and the other end of the t storage refractory material 3 may be connected to the stach valve and to gas recovery equipment. lu this embodiment, the top of the first shell may be connected to the top of the second shell, the outlet for gaseous material being connected to the bottom of the second shell; or the top of the first shell may be connected, as by a gooseneclt to the bottom of the second shell, the outlet for gaseous products being connected to the top of the second shell. Chambers 23 and 23a in Figures 2 and 3 of course, serve as conduit means for carrying material admitted to chamber 21 to chamber 24. Other modifications are possible in the construction of the apparatus without departing from the scope of the invention. For example, it may be desirable, particularly when heavy oil is employed as the gas-making oil, to provide inner perforated refractory linings, such as disclosed in the OKeefe l'tatent Number 2,247,336, in the oilvapor izing zone or zones, through which air and/or steam may be supplied in order to maintain the deposition of carbon at a minimum.

The operation of the process, as stated, is cyclic and comprises in one part of the cycle, burning fluid fuel by blasting an ignited mixture of luid fuel and air downwardly from a point near the top of a confined relatively empty combustion zone toward the bottom thereof, reversing the flow of mixture and leading the resulting hot products of combustion from the top of said space to and through heat storage refractory material storing heat therein; and in another part of the cycle, introducing oil to said confined relatively empty zone, vaporizing said oil @i therein and leading the resulting vaporized oil through the hot heat storage refractory material wherein the oil becomes pyrolyzed to the desired degree and fixed to a stable combustible gas.

The operation of the process in the apparatus shown in -Figure l would commence by forcing air through conduit 6 and oil through conduits 8 and 1t), respectively, to burners 12 and 13, respectively. The combustible mixture of oil and air forced through burners 12 and 13 will be ignited by suitable means, well-known in the art. The resulting dame, as shown in Figure 1, extends downwardly from a point near the top of space 2 toward the bottom thereof and upon reaching a point near the bot tom thereof, reverses itself and the llame and hot combustion products ascend toward the outlet at the top of 2. The length of llame travel provided by this means of operation is thus roughly twice the height of the space 2. Pfhis length of llame travel is sumcient to provide substantially complete combustion of the fuel before the mixture of fuel and air can leave space 2. ln addition, the turbulence induced by this means of operation insures thorough mixing of fuel and air thus further facilitating complete combustion in space 2. The net result of these two features is that substantially complete combustion of the fuel is afforded prior to the heat storage refractory material with the use of a minimum amount of excess air. The hot combustion products which will be primarily carbon dioxide, nitrogen and water vapor, issuing from the top of space 2, then pass through the heat storage refractory material 3 and finally pass through stack valve 4 which is opened to permit the escape of the combustion products ultimately to the atmosphere. Although not shown in the drawings, the combustion products leading through stack valve d may be led through a waste heat boiler in accordance with conventional gas practice, before being `finally vented to the atmosphere. The combustion of the fuel :is continued until the temperature of heat storage refractory material 3 indicates that sufficient heat is stored therein for conducting the gasmahing run.

in conducting the gas-making run in apparatus of the type shown in Figure l, stack valve 4i is closed, and the air supply through conduit 6 is shut off as by closing valve 7. As stated, the apparatus illustrated in Figure 1 is particularly directed to the situation where the fuel employed is oil and may be the same as the malte oil employed in the gasmaking run portion of the cycle. Thus oil for the gas-melting run portion of the cycle, in accordance with this embodiment of the invention, is introduced through conduits il (or Se) and 1l) (or 19a), respectively,

and sprayed into space 2 through burner nozzles 12 and 13 respectively. ln forcing the oil into space 2 during the gasmalting run part of the cycle, the oil becomes vaporized in space 2 because of the high temperatures therein. The oil may also become partially cracked in space 2. ln any event, the vaporized oil and any cracked products thereof leave space 2 through the top thereof and llow through heat storage refractory material 3. Any solid carbonaceous material which may form in space 2 settles to the bottom thereof where it will not interfere with the gas-making operation. This feature is particularly advantageous when high coke-content oil is employed. After excessive amounts of such material have accumulated on the bottom of space 2, it may be removed, as through a door in the bottom part of chamber 1, or by other suitable means.

ln heat storage refractory material 3, the vaporized oil becomes further cracked and pyrolyzed to the desired extent and the cracked products become fixed into a stable, combustible gas. This gas thenleaves through conduit 5 to the wash box and the gas recovery equipment which are not shown in the drawing because they are well known and form no part of the present invention. ln accordance with the preferred practice of the present invention, steam may also be introduced into space 2 during the gas-making run portion of the cycle, as through conduit 14 or conduit 16, or both. This steam mingles with the oil vapors in space 2 and the resulting mixture of steam and vaporized oil pass through heat storage refractory material 3 as described. After the temperature in heat storage refractory material 3 has fallen, but before it has fallen to such an extent that the desired pyrolysis no longer takes place therein, the gas-making portion of the cycle is terminated and the set is again heated as described above.

As stated, the apparatus of Figure l may be in the form of two separate shells. in such case the operation of the cycle is the same as described above, and a conduit will be provided from the top of the shell containing space 2 to one end of the shell containing heat storage refractory material 3, and a stack valve and product gas take-off means will be connected to the other end of the shell containing heat storage refractory material 3.

In the operation of the process in apparatus of the type shown in Figure 2, the cycle may be commenced by forcing air through conduit 31 and fluid fuel through conduit 35 to burner nozzle 39. The resulting combustible mixture is ignited by suitable means, well-known in the art, and the resulting flame is blasted downwardly in space 22 as shown from a point near the top of space 22 toward the bottom thereof. Upon reaching a point near the bottom of space 22, the tiame reverses itself, the llame and the resulting hot products of combustion ascending in turbulent flow toward the point near the top of space 22 where the hot combustion products leave through conduit 27. The hot combustion products then pass into chamber 23 and through the heat storage refractory material contained therein, such as material 26, storing heat therein. The hot gases are then passed through conduit 28 into chamber 24 where they pass through heat storage refractory material 25 storingheat therein. The combustion products then leave chamber 24 through stack valve 29 which is open to lead the combustion products ultimately to the atmosphere. As stated, in connection with Figure l, the combustion products may be led through a waste heat boiler in accordance with conventional gasmaking practice before being vented to the atmosphere.

As stated above, auxiliary heating means may be connected to the top of chamber 23 so that a combustible mixture of fuel and air may be sprayed into the top thereof, supplying additional hot combustion products for heating the set. Such hot combustion products, of course, mingle with thosecoming from space 22 and pass through chamber 23, through conduit 23 and finally through heat storage material 25 in chamber 24 leaving by stack valve 29.

After the temperatures in the set reach a point indicating that suicient heat has been stored therein for conducting the gas-making portion of the cycle, the described heating step is terminated.

The gas-making run portion of the cycle in the apparatus shown in Figure 2 may be commenced by stopping the flow of air and fuel. and by forcing oil into chamber 21 as'through conduit 37 and nozzle 40. As in the case of the apparatus shown in Figure l, separate means for supplying process oil need not be provided where the fuel is oil and is the same as make oil employed in which case the make oil mayalso be introduced through conduit 35 and nozzle 39. The oil sprayed into space 22 becomes vaporized due` to the high temperatures and heat stored inthe lining of chamber 21. A portion of the oil may also become partially cracked in space 22. The vaporized oil passing through conduit 27 and through chamber 23 becomes further cracked, and by the time it has passed through heat storage refractory material 25 of chamber 24, it becomes pyrolyzed to the desired extent and becomes flxedinto a stable combustible gas. The resulting gas is led through conduit 30 to gas recovery equipment which is not shown in the drawing since it may fuel Gil.

be conventional equipment and forms no part of the invention.

As stated above, in connection with the apparatus shown in Figure 2, auxiliary process oil supply means may be connected to the top of chamber 23 and in this case the oil supplied, as through conduit 50 and nozzle 52 may be sprayed into chamber 23 where it becomes vaporized. This vaporized oil mingles with the vaporized oil coming from chamber 21, passing through heat storage refractory material 25 of chamber 24 as described. The refractory material 26, in chamber 23, aids in the vaporization of the oil added through nozzle 40. As stated above, if the fuel employed is oil and the same as the make oil used, the supplemental make oil may be introduced into chamber 23 through conduit 47 and nozzle 49.

The operation of the process in the apparatus of Figure 3 is substantially the same as in that of Figure 2. Since, however, chamber 23a is devoid of heat storage refractory material filling, heat is stored only in the refractory lining and any oil admitted to chamber 23a is vaporized by virtue of the heat stored in the lining.

The foregoing description of the process has dealt with the main steps of the cycle and it will be understood by those familiar with the gas-making art that suitable purges may be made between the principal steps, to clear the system of undesirable gases, to insure greater recovery of the desired gases and to prevent accumulation of explosive mixtures in the system. For example, between the heating step and gas-making run, there is advantageously a brief purging period to force residual combustion products out the stack. This may be accomplished by admitting purging gas, such as steam, through conduit lo (in the apparatus shown in Figure l) or through conduit 41 (in the apparatus shown in Figures 2 and 3).

In addition, it may be desirable, and in some cases preferable, to dilute the oil gas prepared in the described gas-making run portion of the cycle, with gases possessing much lower caloriic value in order to adjust the caloriiic value, specific gravity and other characteristics of the final gas product. In this connection, some of the products of combustion formed during the heating step of the cycle may be led to the gas recovery equipment. However, if such dilution is to be practiced, it is preferred that the dilution gases be products of incomplete combustion of the fuel. Thus, there may be interposed, during the cycle, either before or after the gas-making step, a brief step during which fluid fuel is forced into the combustion chamber and burned in the presence of insufficient air for complete combustion, with the resulting products of incomplete combustion being led through the system to the gas recovery equipment. This can readily be accomplished by conducting part of the abovedescribed heating step with the stack valve closed and employing insufficient air for complete combustion of the Since this combustion, even in the presence of nsuicient air, is exothermic, such a step may be relied upon to supply a portion of the heat required during the cycle.

Referring to the fuel employed during the heating step, it may be any iiuid fuel such as those ordinarily employed in the gas-making industry, for instance petroleum oil, tar, combustible gas, and the like. Preferably the fuel employed will be a petroleum oil and a wide variety of such oils is available for this use, ranging from relatively light distillates through Numbers 2 and 3 furnace oils, to heavy residual oils, and the like.

The present process and apparatus permit the utilization of a wide range of gas-making oils. The gas-making oil employed may range from light hydrocarbon oils, such as propane, butane, kerosene, and the like, medium oil, ranging from the gas oils or diesel oils, through the heavier residuum oils and crude oils. rEhe present invention is particularly applicable to the heavier residuum oils that may produce heavy coke and other carbonaceous deposits when gasified, since such material may accumulate on the bottom of the combustion zone without fouling the equipment enough to interfere with the gasmaking operation.

The average temperatures employed during the cycle will be similar to those employed during conventional procedures; for example, the average temperature in the heat storage refractory material may range, depending on the type of oil employed, the degree of pyrolyzing required and the contact time provided, from as low as about 1300 F. to as high as about 2400 F. As stated, these are average temperatures and it will be understood that at various times during the cycle the temperature in heat storage refractory material may drop below the stated range or may be above the stated range. The temperature in the combustion zone will generally be some what higher than those in the heat storage refractory material and may range from about 1800" F. to about 2900" F. Again it will be realized that, toward the end of the heating step, temperatures may be above this range, and also that at the end of the gas-making run, temperatures in the combustion zone may drop below the stated range. However, as is conventional in the art, care is taken to prevent the temperature in the combustion zone from falling so low that at the beginning of the heating step, faulty ignition is encountered.

Considerable modification is possible in the selection of the various reactants, and of the fuel, and in the arrangement of the parts of the apparatus without departing from the scope of the invention.

I claim:

1. A method for the manufacture of oil gas involving alternating heating and oil-pyrolyzing steps in three chambers the first of which is relatively empty and is in fluid tiow communication from a point near the top thereof to one end of the second chamber, and the third chamber containing heat storage refractory material and being in fluid flow communication with the other end of said second chamber, which comprises, in one part of the cycle, forcing an ignited mixture of fluid fuel and air in an amount suflicient to provide substantially complete combustion of said fuel downwardly in said first chamber from a point near the top thereof whereby the resulting flame descends toward the bottom of said first chamber, reverses itself and then ascends toward the top of said first chamber, storing heat in said first chamber; withdrawing the resulting hot products of combustion from a point near the top of said first chamber, and passing said hot products of combustion serially through said second chamber and through said third chamber, storing heat therein; and, in another part of the cycle, introducing oil to said rst chamber, vaporizing the oil therein; withdrawing said Vaporized oil from a point near the top of said first chamber; passing said vaporized oil serially through said second chamber and through said third chamber, pyrolyzing said oil therein into a com bustible gas, and withdrawing said combustible gas from said third chamber to storage.

2. The process of claim 1 wherein, during said oilpyrolyzing step additional oil is introduced directly to said second chamber.

3. The process of claim 2 wherein, during said heating step, auxiliary fluid fuel and air are introduced directly to said second chamber for combustion therein.

4. A method for the manufacture of oil gas involving alternating heating and oilpyrolyzing steps in three charnbers the first of which is relatively empty and is in fiuid flow communication from a point near the 'top thereof to one end of the second chamber, and the third chamber containing heat storage refractory material and being in fluid flow communication with the other end of said second chamber, which comprises, in one part of the cycle, forcing an ignited mixture of fluid fuel and air in an amount sufficient to provide substantially complete combustion of said fuel downwardly in said first chamber from a point near the top thereof whereby the resulting flame descends toward the bottom of said first chamber, reverses itself and then ascends toward the top of said first chamber, storing heat in said first chamber; withdrawing the resulting hot products of combustion from a point near the top of said first chamber, and passing said hot products of combustion serially through said second chamber and through said third chamber storing heat therein; and, in another part of the cycle, injecting oil downwardly intosaid first chamber from a point near the top thereof, vaporizing the oil therein; withdrawing said vaporized oil from a point near the top of said first chamber; passing said vaporized oil serially through said second chamber and through said third chamber, pyrolyzing said oil therein into a combustible gas, and withdrawing said combustible gas from said third chamber to storage.

5. The process of claim 4 wherein, during said oilpyrolyzing step additional oil is introduced directly to said second chamber.

6. The process of claim 5 wherein, during said heating step, auxiliary fluid fuel and air are introduced directly to said second chamber for combustion therein.

References Cited in the file of this patent UNITED STATES PATENTS'` 1,157,225 Jones Oct. 19, 1915 1,591,891 Sklovsky July 6, 1926 1,836,627 Sufern Dec. 15, 1931 1,971,729 Perry Aug. 28, 1934 2,042,998 Johnson June 2, 1936 2,118,096 McIntire et al May 24, 1938 2,131,696 Brandegee et al Sept. 27, 1938 2,192,815 Johnson et al. Mar. 5, 1940 2,297,696 Elder et al. tDct. 6, 1942 

1. A METHOD FOR THE MANUFACTURE OF OIL GAS INVOLVING ALTERNATING HEATING AND OIL-PYROLYZING STEPS IN THREE CHAMBERS THE FIRST OF WHICH IS RELATIVELY EMPTY AND IS IN FLUID FLOW COMMUNICATION FROM A POINT NEAR THE TOP THEREOF TO ONE END OF THE SECOND CHAMBER, AND THE THIRD CHAMBER CONTAINING HEAT STORAGE REFRACTORY MATERIAL AND BEING IN FLUID FLOW COMMUNICATION WITH THE OTHER END OF SAID SECOND CHAMBER, WHICH COMPRISES, IN ONE PART OF THE CYCLE, FORCING AN IGNITED MIXTURE OF FLUID FUEL AND AIR IN AN AMOUNT SUFFICIENT TO PROVIDE SUBSTANTIALLY COMPLETE COMBUSTION OF SAID FUEL DOWNWARDLY IN SAID FIRST CHAMBER FROM A POINT NEAR THE TOP THEREOF WHEREBY THE RESULTING FLAME DESCENDS TOWARD THE BOTTOM OF SAID FIRST CHAMBER, REVERSES ITSELF AND THEN ASCENDS TOWARD THE TOP OF SAID FIRST CHAMBER, STORING HEAT IN SAID FIRST CHAMBER; WITHDRAWING THE RESULTING HOT PRODUCTS OF COMBUSTION FROM A POINT NEAR THE TOP OF SAID FIRST CHAMBER, AND PASSING SAID HOT PRODUCTS OF COMBUSTION SERIALLY THROUGH SAID SECOND CHAMBER AND THROUGH SAID THIRD CHAMBER, STORING HEAT THEREIN; AND, IN ANOTHER PART OF THE CYCLE, INTRODUCING OIL TO SAID FIRST CHAMBER; VAPORIZING THE OIL THEREIN; WITHDRAWING SAID VAPORIZED OIL FROM A POINT NEAR THE TOP OF SAID FIRST CHAMBER; PASSING SAID VAPORIZED OIL SERIALLY THROUGH SAID SECOND CHAMBER AND THROUGH SAID THIRD CHAMBER, PYROLYZING SAID OIL THEREIN INTO A COMBUSTIBLE GAS, GAS WITHDRAWING SAID COMBUSTIBLE GAS FROM SAID THIRD CHAMBER TO STORAGE. 